1. Field of the Invention
This invention generally relates to an ink jet recording head for effecting recording by discharging liquid called ink and an ink jet recording apparatus having such ink jet recording head, and more particularly to an ink jet recording head having high-speed responsiveness and excellent discharge stability and an ink jet recording apparatus having such ink jet recording head.
2. Related Background Art
There is known an ink jet recording method which effects recording by causing recording liquid to be discharged and fly. This method has excellent features in that high-speed printing is possible, that noise produced is low and the quality of recording is high and moreover color image recording is easy, and that recording can be done on plain paper or the like.
Such an ink jet recording method uses ink jet recording heads based on various liquid discharge principles to accomplish recording, and it is popular that as energy generating means generating energy utilized to discharge liquid, use is made of an electro-mechanical converting member or an electro-thermal converting member shown in Japanese Laid-Open Patent Application No. 59936/1979.
As an example of the ink jet recording method shown, for example, in Japanese Laid-Open Patent Application No. 59936/1979, there is a method whereby a pulse current is imparted to an elector-thermal converting member provided in a liquid path to cause a state change by heat to occur to recording liquid and the recording liquid is discharged from a discharge port on the basis of said state change to thereby accomplish recording. On whatever principle it may be based, to obtain a practical performance as a recording apparatus, it is required to be able to repetitively discharge the liquid with high-speed responsiveness of 1 KHz-10 KHz.
To cause such an ink jet recording head to repetitively discharge the liquid, the amount of liquid lost by the discharge must be supplemented by the time of next discharge. A typical method thereof is to utilize the surface tension of the liquid and direct the liquid to the discharge port by capillary phenomenon.
Accordingly, to drive the energy generating means at a high frequency to thereby accomplish high-speed recording, it is necessary to provide structure which readily permits the discharge port to be replenished with liquid, that is, structure in which the length of the liquid path is short and the cross-sectional area of the liquid path is great, that is, the liquid path resistance is small. However, if the liquid path resistance is made small, energy loss upstream of the liquid path occurs during the generation of the energy utilized to discharge the liquid, to hamper the effective contribution of said energy to the liquid discharge, and this has led to a slow discharge speed of the liquid or a small diameter of liquid droplets, which in turn has sometimes resulted in a low quality of recording. In other words, there has sometimes arisen the problem that an attempt to increase the drive frequency results in a slow discharge speed and an attempt to improve the discharge speed fails to increase the frequency from the necessity of increasing the liquid path resistance to thereby minimize the loss of energy, and with the conventional ink jet recording head, it has sometimes been the case that rapid and stable recording becomes difficult.